Parental fitness

Mean-field theory can be used to predict the effects of mutation rate and parent fitness on the moments of the mutant fitness distribution (Voigt et al, 2000a). In this analysis, only the portion of the mutant distribution that is not dead (zero fitness) or parent (unmutated) is considered. The mutant effects are averaged over the transition probabilities without the cases of mutations to stop codons or when no mutations are made on a sequence. In order to obtain the fitness distribution, two probabilities are required (1) the probability pi(a) that a particular amino-acid identity a exists at a residue i, and (2) the transition probability that one amino acid will mutate into another Q = 1 — (1 — pm)3. The probability vectors p a) can be determined through a mean-held approach (Lee, 1994 Koehl and Delarue, 1996 Saven and Wolynes, 1997). The amino acid transition probabilities Q are calculated based on the special connectivity of the genetic code and the per-nucleotide mutation rate. Removing transitions to stop codons and unmutated sequences only requires the proper normalization of the probabilities pi and the moments. For example, the first moment of the fitness improvement w of the uncoupled fitness function is written as... 

Mean-field theory can be used to predict the effects of mutation rate, landscape ruggedness, and parental fitness on the moments of the mutant fitness distribution1791. In this analysis, only the portion of the mutant distribution that is not dead (zero fitness) or parent (unmutated) is considered. The mutant effects are averaged over the transition probabilities. In order to obtain the fitness distribution, two sets of probabilities are required (1) the probabilities P (o) that a particular amino acid identity o exists at a residue i, and (2) the transition probabilities that one amino acid... 

The random number generator produeed the following values 0.326, 0.412, 0.862 and 0.067. Henee Parent 1 was seleeted twiee. Parents 2 and 4 onee and Parent 3 not at all. The seleeted parents were randomly mated with random ehoiee of erossover points. The fitness of the first generation of offsprings is shown in Table 10.2. 

The Vaughan-Williams classification of antiarrhythmic drugs has been criticized for a number of reasons. The classification is based on the effects of drugs on normal, rather than diseased, myocardium. In addition, many of the drugs may be placed into more than one class. For example, the class IA drugs prolong repolarization/refractoriness, either via the parent drug8,9 or an active metabolite,10 and therefore also maybe placed in class III. Sotalol is also a 3-blocker, and therefore fits into class II. Amiodarone inhibits sodium and potassium channels, is a non-competitive inhibitor of 3-receptors, and inhibits calcium... 

Select the string with the greater fitness and copy the string into the parent pool. 

The wheel is spun and the string into whose slot the virtual ball falls is copied once into the parent pool. This procedure is repeated npop times to pick the full complement of parent strings. In roulette wheel selection, every string has a nonzero chance of being picked, proportional to its fitness, so even the poorest string may be chosen as a parent. The method also preferentially selects the fitter strings and, because of these features and its simplicity, roulette wheel selection is widely used. 

As a result of this scaling, all strings that previously had a raw fitness above the mean will have a scaled fitness greater than 1, while the fitness of every below-average string will be less than 1. Each string is then copied into the parent pool a number of times equal to the integer part of its scaled fitness (Table 5.8). 

Note fi rml is the raw fitness of a string,fsalM is its scaled fitness, Ci/Xrtatn is the number of parent strings guaranteed to be made by stochastic remainder,/) resiM is the residual fitness after the number of parents made has been subtracted from the scaled fitness, is the... 

For each string whose scaled fitness is at least 1.0, copy the string into the parent pool a number of times equal to the integer part of its fitness. 

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